Table 2.

Serum contents of trace elements in healthy group in high, middle and low gastric cancer incidence areas (^-x ± s)

	n	Zn(mg/L)	Cu(mg/L)	Se(μg/L)	Cu/Zn
High (I)	152	0.886 ± 0.015	0.911 ± 0.015	84.82 ± 2.18	1.065 ± 0.025
Middle (II)	95	0.885 ± 0.015	0.942 ± 0.019	84.57 ± 1.23	1.099 ± 0.035
Low (III)	152	1.002 ± 0.019	0.867 ± 0.032	76.87 ± 3.22	0.867 ± 0.033
Analysis of variance		F = 9.326	F = 2.479	F = 2.297	F = 9.939
		P = 0.00012	P = 0.086	P = 0.102	P = 0.000066
Newmen-Keul test in	I:III	q = 5.782a			q = 6.827a
comparison of different	I:II	q = 0.0303			q = 0.955
areas	II:III	q = 5.456a			q = 6.105a

^aP < 0.01.